Draw ring



- L. R. PEASE Feb. 22, 1944.

DRAW RING Filed Aug. 4, 1941 INVENT 15575;? R. BY 2 I on sheet material.

Patented Feb. 22, 1944 DRAW RING Lester R. Pease, Inglewood, Calif asslgnor to Northrop Aircraft, Ina,

Hawthorne, {tam a corporation of California Application August 4, 1941, Serial No. 405,424

Claims.

My invention relates to flange forming dies and more particularly to tools designed primarily for use on hydraulic presses having rubber platens.

The main object of my invention is to provide a draw ring assembly .for use primarily in conjunction with hydraulic presses having a rubber platen, which is ideally adapted for forming flanges, either open, straight, curved or closed,

My invention is also particularly advantageous for use in making parts for metal airplanes.

Other objects of my invention will be appai ent or will be specifically pointed out in the de= scription forming a part of this specification, but I do not limit myself to the embodiment of the invention herein described, as various forms may be adopted within the scope of the claims.

In the drawing:

Fig. l is a top view in elevation of one preferred form of my invention for providing a curved flange on a part of particular shape.

Fig. 2 is a cross sectional view or the device, taken as indicated by the line 2-2 in Fig. 1, the die being shown positioned on the bed plate of a hydraulic rubber platen press.

Fig. 3 is a view similar to that of Fig. 2, showing the relation of parts after the flange has been formed.

In making parts for metal airplanes it is customary in many cases to utilize a hydraulic press having a heavy fiat bed plate and an overhead rubber platen, this platen being raised and lowered by a large hydraulic cylinder. When certain types of draws are required to be formed in sheet material, the rubber is forced with high pressure against the sheet positioned over a female mold on the bed plate so that the sheet is forced to take the contour of the mold. However, it is obvious that such a deviceis limited as to type of draw that can take place, and as far as known only straight flanges have been made on sheets with this type of press.

However, my invention herein to be described, is adapted for making curved and closed flanges on such a press, and broadly comprises a form block over which the work sheet may be positioned. together with surrounding draw rings which are capable of being opened and closed to receive the work sheet or blank, the assembled device then being placed between the base block and the rubber platen of the hydraulic press, and pressure applied to the assembly to complete the formation of the flange.

My invention may be more readily understood through apertures t in the metal sheet blank 5, to iormed.

this case There shown my blank as having one curved edge '3 which is to be turned down as a continuous flange, and an opposite edge tl on which no flange is to be formed.

Two draw rings are provided, an upper draw ring l ll and a lower draw ring ll, these draw rings being provided with matching hinge lobes l2 and i3 held together by pins it, so that the draw rings may be opened and closed. Opposite the lfnnges is positioned a locking bracket it attached to the lower draw ring ll through which a tapered pin ll may be passed, entering the upper draw ring. The upper draw ring is provided with a vertical bore it into which the end of taper pin ll projects, so that the taper pin may easily be removed.

in case sheet material greater than approximately .05 inch is to be utilized in the blank 5, I prefer to provide a spacer 2d between the draw rings, the spacer being cut out to surround the blank it with sufficient clearance so that the blank 5 may be placed on the lower draw ring within the aperture. This spacer is preferably to be the same thickness as the sheet to be formed, and may be spot welded to the lower draw ring H to hold it in proper position. The inside of the draw rings Ill and H are dimensioned to accommodate the thickness of the material only where the part'is to be flanged. The inside faces are polished, the edges are slightly broken to prevent'scratching the mate-= rial. The width of the draw rings X dimension, as shown in Fig. 1, preferably is slightly greater than the width of the flange to be formed.

In operation the taper pin ll is removed so that the draw rings may be opened. The blank 5 is placed on the lower ring. The draw rings are then closed, with the blank within the spacer if used, and the draw rings are locked with the 2 blank inside by driving the taper pin l7 into position.

.The locked draw rings are then placed on the form block, with pins 3 in apertures 4. In the case of the form shown no part of the straight edge of the blank will be included between the draw rings, but the curved edge I will be included in the draw rings around the entire extent thereof.

The flnal assembly as shown is then placed on the bed plate 2| of the hydraulic press and 2. A die assembly comprising, in combinatlon with a work sheet, a form block havin the rubber platen 22 thereof forced under high pressure against the draw rings and the upper portion of the die. The fluid action of the rubber tends to centralize the draw ring and forces the metal against the form block as shown in Fig. 3. Also the forming action of the rubber permits a wide latitude of error between the draw rings and the form block. Pressure is continued until the flanging is complete. The rubber platen is then retracted and the formed part removed.

It has been found that by the use of a draw ring assembly as just above described, flanges can bemade on presses having rubber platens with excellent accuracy and at a relatively high production. The assembly just above described is cheap to make, eflicient in operation and can be made, for example, from boiler plate and sheet iron stock.

As rubber platen hydraulic presses usually have an extended platen and bed area, and as the fianging die assembly I have described does not need to be attached to either the bed or platen, a number of my flanging asesmblies may be-loaded and operated on by the press simultaneously; Also if flanges of different heights are to be made, the support block may be changed accordingly.

- While I have described my invention asbeing primarily adapted for use on hydraulic presses having rubber platens, it must also be realized that the device of my invention can be used for forming 90 bends on straight flanges, by applying pressure to the draw ring only. It is obvious, however, that the use of the rubber platen is highly advantageous, in that it permits the forming of closed flanges and flanges continuously formed around a curved edge, as well as open and straight flanges.

I claim:

1. A flanging die assembly comprising, in combination with a work sheet, a form block having a periphery oi predetermined contour, a pair of draw rings having registering apertures therein, means for locking said draw rings together with a portion of said work sheet to be flanged included therebetween, a spacer plate of work sheet thickness between said draw rings and apertured to fit said work sheet, and means for positioning said work sheet on said form block with one of said draw rings surrounding said form block, the inner edges of said apertures following the contour of said form block with a clearance there-v between of work sheet thickness adjacent the portion to be flanged only.

form block, a. base a resilient platen positioned over said assembly,

a periphery of predetermined contour, a pair of draw rings having registering apertures therein, means for locking said draw rings together with a portion of said work sheet to be flanged included therebetween, means for positioning said work sheet on said form block with one of said draw rings surrounding said form block, the inner edges of said apertures following the contour of said form block with a clearness therebetween of work sheet thickness adjacent the portion to be flanged onhr, a base beneath said flanging die assembly, a resilient platen positioned over said assembly, and means for forcing said platen against said assembly to force both of said draw rings over said form block thereby flanging the included portion of said work sheet.

3. A flanging die assembly comprising, in combination with a work sheet, a form block having a periphery of predetermined contour, a pair of draw rings having registering apertures therein, means for locking said draw rings together with a portion of said work sheet to be flanged included therebetween, means for positioning said work sheet on said form block with one of said draw. rings surrounding said form block, the inner edges of said apertures following the contour of said form block with a clearness therebetween of work sheet thickness adjacent the portion to be flanged only, a support block posi-' tioned beneath said form block, and of uniformly smaller dimensions around in a. plane parallel to the general plane of said beneath said support block,

and means for forcing said platen against said assembly to force both of said draw rings over said form blocks and said support block thereby flanging'the included portion of said work sheet.

4. A flanging die assembly for drawing and flanging sheet material, comprising a form block having a periphery of predetermined contour, a pair of draw rings-having registering apertures therein and adapted to receive said form block therethrough, means for holding said draw rings together with a portion of such sheet material included therebetween, the inner edges of said apertures following the contour of said form block with a clearance therebetween of the thickness of such sheet material adjacent the portion only of the material which is to be flanged, means for forcing said form block through the apertures in said draw rings to draw and flange suchsheet material and free such sheet material from said draw rings, and a resilient block in the path of relative movement of said form block to resist such relative movementof said form block and form itself about said form block to conform said sheet material to said form block.

5. Apparatus in accordance with claim 4 wherein said draw rings are provided with a hinge at one side thereof and with a lock on that side opposite said hinge.

LESTER R. PEASE.

the periphery thereof, 

